Texas Exits (Was: Is Light Rail really...
Silas Warner
> I've studied the freeway problems in both the morning and afternoon "rush
> hours." The problem is not necessarily the wideness of the freeway but the
> number of entrance ramps. If they would simply close them at the points
> where the freeway starts to back up, congestion would be greatly reduced.
This is a good point to describe the curious construction of Houston
freeways and the phenomenon of the "Texas Exit." Freeways in Houston
start as widely-spaced pairs of arterial streets, like this
(ASCII art follows)
--------+------------------------------+-----------
| |
| |
| |
--------+------------------------------+------------
The next step is to construct overpasses in the center between
the cross-streets:
--------+------------------------\\----+-------//--
\ ========/ \\==========//
| |
/=========\ //==========\\
--------+------------------------//----+-------\\---
and the final step is to join the overpasses together
into the freeway, like this:
--\\----+------//----------------\\----+-------//--
===\\=========//==================\\==========//===
| |
===//=========\\==================//==========\\====
--//----+------\\----------------//----+-------\\---
Now you can see from this that to exit at a given cross
street, you actually leave the freeway on the frontage road
at the interchange BEFORE the cross-street you want. You
wind up traveling a mile or so on the congested frontage
road before turning into the cross-street. Furthermore the
frontage roads are separated from the freeways by only a
strip of grass -- not even a drainage ditch.
So, Texans tend to exit these freeways not at the marked
exit ramps but wherever they feel the urge to cut across
the grass. The result is well-marked grass paths -- "Texas
Exits" on the majority of Houston freeways.
Silas Warner
Fmtyner
>freeways and the phenomenon of the "Texas Exit." Freeways in Houston
>start as widely-spaced pairs of arterial streets, like this
>(ASCII art follows)
>
>--------+------------------------------+-----------
> | |
> | |
> | |
>--------+------------------------------+------------
>
>The next step is to construct overpasses in the center between
>the cross-streets:
>--------+------------------------\\----+-------//--
> \ ========/ \\==========//
> | |
> /=========\ //==========\\
>--------+------------------------//----+-------\\---
>
>and the final step is to join the overpasses together
>into the freeway, like this:
>
>--\\----+------//----------------\\----+-------//--
>===\\=========//==================\\==========//===
> | |
>===//=========\\==================//==========\\====
>--//----+------\\----------------//----+-------\\---
>
>Now you can see from this that to exit at a given cross
>street, you actually leave the freeway on the frontage road
>at the interchange BEFORE the cross-street you want. You
>wind up traveling a mile or so on the congested frontage
>road before turning into the cross-street.
The construction order sounds like "staged construction". Building frontage
first is a Texas phenomon I haven't seen anywhere else.
As for the exit ramp configuration, I've heard them called "X-diamonds" They
can be found on I-35 Stemmons Freeway in Dallas. A man told me that when he
commuted from Kingwood to Houston, the "X-Diamond" lane of US-59 was like an
extra lane. Since the main lanes were congested, people were following this
lane as it wandered between the freeway and the frontage road (without traffic
signals or yield signs)!
>Furthermore the
>frontage roads are separated from the freeways by only a
>strip of grass -- not even a drainage ditch.
>
>So, Texans tend to exit these freeways not at the marked
>exit ramps but wherever they feel the urge to cut across
>the grass. The result is well-marked grass paths -- "Texas
>Exits" on the majority of Houston freeways.
>
I've never seen this in Dallas. I'll have to look for it sometime.
> Silas Warner
>
>
Fred Tyner
Dallas, TX
hiwa...@my-dejanews.com
fmt...@aol.com (Fmtyner) wrote:
> The construction order sounds like "staged construction". Building frontage
> first is a Texas phenomon I haven't seen anywhere else.
SH 151 in west San Antonio is in the midst of this process right now. About
half of the cross streets now have the overpasses built and in use- the rest
is still just frontage road. I've got a couple of pictures of this in the
camera- after my trip, I'll get them developed and on my site.
> As for the exit ramp configuration, I've heard them called "X-diamonds" They
> can be found on I-35 Stemmons Freeway in Dallas. A man told me that when he
> commuted from Kingwood to Houston, the "X-Diamond" lane of US-59 was like an
> extra lane. Since the main lanes were congested, people were following this
> lane as it wandered between the freeway and the frontage road (without traffic
> signals or yield signs)!
I've seen this- these people don't realize that they're actually adding to the
congestion.
> >Furthermore the
> >frontage roads are separated from the freeways by only a
> >strip of grass -- not even a drainage ditch.
> >
> >So, Texans tend to exit these freeways not at the marked
> >exit ramps but wherever they feel the urge to cut across
> >the grass. The result is well-marked grass paths -- "Texas
> >Exits" on the majority of Houston freeways.
> >
> I've never seen this in Dallas. I'll have to look for it sometime.
I don't see too much of this in SA- oops, I mean San Antonio :-) - either. I
think most people realize that the frontage roads here, with those *long*
cycle signals, will take just as long or longer than the mainlanes during
regular congestion. I do see quite a few median jumpers when there's
congestion on rural Interstates, however, especially on I-35 north of here on
holiday weekends. These people exemplify the immaturity and impatience that
creates so many problems on our highways today. </rant>
--Brian Purcell
The Texas Highwayman
San Antonio, Texas, USA
mailto:hiwa...@express-news.net
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